Pteronisculus is anextinctgenus of prehistoricray-finned fish that lived during theEarly Triassic andMiddle Triassicepochs of theTriassicperiod worldwide.[3]
It was first described under the name "Glaucolepis" byErik Stensiö in 1921 and was later shown to be asynonym ofPteronisculus described byErrol White in 1933. However, because the name "Glaucolepis" is preoccupied (it had already been given to the extantlepidopteran insectGlaucolepis Braun, 1917),Pteronisculus became the valid genus name for the Triassic fish.[2]
Like many other early ray-finned fishes,Pteronisculus had a bullet-shaped skull with large eyes near the front end, and a largegape armed with small to large, conical teeth. Its body was covered with small rhombic scales that show peg-and-socket articulation.Pteronisculus had enlargedpectoral fins and smallpelvic fins. Thedorsal andanal fins were virtually opposed to each other. Thecaudal fin washeterocercal.[3][4]
Pteronisculus had a wide geographic range during the Early Triassic.[1] Fossils were collected inGreenland,Madagascar,Spitsbergen and theUnited States. It is possibly also present in the Early Triassic ofBritish Columbia,Canada; a species described asAcrolepis laetus byLawrence Lambe has been tentatively referred toPteronisculus. From the Middle Triassic, it is only known from SouthChina.[3][4][5] Its occurrence in thePermian ofSouth Africa has been questioned.[3] About 13 species have been described to date, ranging from 11 centimetres (0.36 ft) to 40 centimetres (1.3 ft) in length.
Pteronisculus was originally referred to thefamilyPalaeoniscidae, but was removed due to differences toPalaeoniscum.[4] Based on similarities with theLate TriassicTurseodus, it was provisionally included inTurseoidae.[3] Asynapomorphy ofPteronisculus andTurseodus is the tooth-bearinglachrymal. However,Turseodus is incompletely known and a close relationship withPteronisculus has not yet been tested with acladistic analysis. In the cladistic analysis by Ren & Xu,[5]Pteronisculus was recovered in asister group relationship with theCarboniferousCyranorhis, a genus that has been referred to the probablyparaphyletic familyRhadinichthyidae.
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